JPS6236415B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fault section search method when power supply is cut off or a similar fault occurs in a communication transmission system that performs DC series power supply.

Figure 1 shows an example of the coaxial cable transmission system in Japan. In the figure 11,1
1', 12, 12' are constant current sources for power supply, and 12, 12' may be omitted in some cases. 2
are transmission lines, 31, 3i, 3n, 31', 3i',
3n' is a repeater, and 4 is a power separation filter (PSF) that separates DC and signals.
5 is a constant voltage diode for supplying a constant voltage to the repeater. A device for signal relay other than a transmission line, in this example a repeater PSF and a constant voltage diode, is called a repeater. the current,
Various transmission systems have been put into practical use, but if we focus only on the power supply system for systems in which repeaters are fixed and electronic, the basics are of this type, although there may be some variations.

Now, in the system shown in Figure 1, there is some kind of failure, for example, transmission line 2 is damaged due to construction or the like.
If the wire is disconnected at any of the locations, the power supply from the constant current source 11 etc. is stopped, and all repeaters stop operating. For this reason, it is not possible to obtain any information through the relay device, let alone the location of the failure.
It is not possible to determine whether a disconnection occurred between any relay equipment, and in addition, in large-capacity transmission systems such as the coaxial analog 60 MHz system or the coaxial PCM 400 M bit system, the interval between manned stations is 100.
Km and the number of intermediate relay devices is more than 60, so a delay in discovering the fault zone will result in a delay in functional recovery of the transmission line, leading to a serious deterioration of service. In order to solve these problems, conventional fault section search methods have been developed, such as a method that measures the capacitance of the power supply circuit in the fault section, and a method that uses a pulse echo tester that passes through the power supply circuit. Regarding the former, line disturbances that indicate insulation resistance are rare enough to perform accurate capacitance measurements, and regarding the latter, in transmission systems where the cutoff frequency of the power separator is low, the pulse waveform is severely rounded and accuracy is poor. It had the drawback of not being able to climb.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a fault section search method that accurately determines a fault section at low cost and easily.

The fault section search method of the present invention is directed to the relay device on the transmitting side of a communication transmission system in which DC series power is supplied via a transmission line to a plurality of relay devices provided with power separators on the input side and output side of the repeater. a first current detecting means for detecting a feeding current in a feeding system path between the power separator and the repeater on the output side and temporarily turning off a first switch element; A second current detecting means for detecting and disconnecting the second switch element is inserted in series, and the series circuit with the first and second switch elements is connected to the first and second current detecting means. It is connected between the connection point of the detection means and the power supply system line on the input side of the repeater of the repeater in the opposite direction, and by forcibly restarting the power supply in the event of a power failure, While the first switch element of the relay device is temporarily disconnected, if a loop is formed in the power supply path after the relay device, the power supply current is transferred to the second current detection means. The present invention is characterized in that the power supply circuit is looped back at the transmitting/receiving relay device immediately preceding the point of failure in the relay transmission line system, thereby making it possible to determine the faulty section.

FIG. 2 shows an embodiment of the present invention, and for convenience of explanation, the constant current source for power supply is the constant current source 11 of FIG.
11', and when viewed from this constant current source, the side that transmits the signal is called the transmitting side (the transmission line going from the left in Figure 1), and the side that receives the signal is called the receiving side (the left-going transmission line).
It will be called.

In the embodiment shown in FIG. 2, a part of the power supply circuit of the transmission side relay device, that is, after the power supply current passes through the relay device,
Before entering PSF, connect relays Ai, Bi and Ak, Bk, and connect contact a from the connection point of these relays.
The PSF of the receiving side repeater power supply circuit and the middle of the repeater input are connected in a shunt through _i , b _i and a _k , b _k . Furthermore, to ensure the operation of relays Ai, Ak, Bi, and Bk, capacitors C and C' are connected in parallel, but this is especially necessary if the characteristics of the relay itself satisfy the following operations. There isn't. Furthermore, the contacts a _i and a _k of relays Ai and Ak are,
This is a temporary disconnection due to relay operation, but compared to this disconnection time, relay Bi,
The operations of contacts b _i and b _k of Bk should be selected to be sufficiently short. Capacitors C and C' connected to relays Ai, Ak, Bi, and Bk are used to delay recovery after a certain period of time by discharging charges from C and C'. Further, the state of the contacts in FIG. 2 shows a non-power-supplied state.

First, let's talk about the state when the power supply is turned on when the system is normal. Repeater 3i, 3i' left side is line 2
connected to the power supply device through the relay 3k,
Assume that 3k' is an adjacent station of 3i and 3i'. First, when power supply is started, a positive voltage and current are applied to the repeater 3i side and a negative voltage and current to the 3i' side. At this time, the power supply current flows through the repeater 3i, the relay Ai, the contacts a _i and b _i , and the repeater 3i. Therefore, Ai is activated and contact a _i is temporarily disconnected. However, in the downstream relay device, since Ak is not activated and contacts a _k and b _k are closed, the power supply current is transferred to the relay as contact a _i is disconnected.
It is transferred to the downstream repeater 3k through Bi. As mentioned above, contact b _i is selected to operate until contact a _i becomes connected again, and is disconnected, so contact a
The series circuit of _i and b _i remains disconnected. Exactly the same process is repeated for the relay devices including the repeater 3k, and if the system is normal, the above operations are repeated one after another to complete power supply to all repeaters.

Next, let us consider a case where a failure occurs that causes the power supply to be cut off after the repeater 3k, that is, on the right side. However, it is assumed that the repeaters 3i, 3k, etc. are located at arbitrary locations. Generally, when a power supply abnormality occurs, the power supply is cut off to protect the equipment. When a maintenance person discovers a transmission line disconnection due to such a power supply abnormality, in this embodiment, an attempt is made to restart the power supply. At this time, except for the station immediately before the failure, that is, the repeater 3k, the relays operate sequentially in the same manner as described above, and power is supplied to the repeater for both transmission and reception. However, at repeater 3k, even if contact a _k is temporarily disconnected, the power supply current cannot be transferred to relay Bk. However, relay Ak starts operating after a certain time due to parallel capacitance C, but its own contact a
Even while _k is disconnected, the operation continues to discharge charges from capacitor C and it becomes connected again. While the contact a _k is disconnected, the current in the B relay Bj of the front relay device is also disconnected, but the capacitance C' of each B relay is charged until the relay contact a _k is connected again, and this charge is released, so contact point b _j in each preceding relay device will not recover and become connected.

In this way, the power supply system is looped at the relay device immediately preceding the failure point, and the relay devices in the section up to this point recover their functions. Therefore, in transmission systems that have a supervisory signal oscillator in the repeater, the power supply voltage can be determined by monitoring this supervisory signal on the receiving side, and in systems without this, by measuring the power supply voltage. Since it is proportional to the number of repeaters supplied with power, it is possible to immediately determine the faulty section.

Next, we will discuss the case where power is supplied from both ends as shown in Figure 1. If power is supplied from both ends with the configuration shown in Figure 2, all repeaters on the left side of the fault point, that is, the constant current sources 11 and 11', will be supplied with power, but the relays on the right side, that is, the constant current sources Even if power is supplied from the source 12, 12' side, if the circuit remains as it is, no power will be supplied to any of the repeaters. It is sufficient to judge faults from one direction, but if judgment from both directions is required, as in the embodiment shown in Fig. 3, the transmission side relay in the embodiment shown in Fig. 2 A diode D' may be inserted into a device similar to the shunt path and connected symmetrically to prevent current from flowing in the opposite direction. However, in FIG. 3, the additional circuit for controlling relay characteristics is omitted.

It goes without saying that by using the electronic circuit of the relay in this embodiment, a compact and highly reliable relay can be realized.

As described above, according to the present invention, a disconnection fault section can be determined with a simple configuration, which greatly contributes to labor saving, efficiency, and improvement of serviceability in transmission line maintenance work.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a general coaxial cable transmission system, and FIGS. 2 and 3 are circuit diagrams showing embodiments of the present invention. 11, 11', 12, 12'... Constant current source for power supply, 2... Transmission line, 31, 31' to 3n, 3
n′...Repeater, 4...PSF, 5...Voltage regulator diode, Ai, Bi, Ak, Bk...Relay, a _i , b _i ,
a _k , b _k ...Contact points of Ai, Bi, Ak, Bk, C, C'...
...capacitor.

Claims (1)

[Claims] 1. The relay device on the transmitting side of a communication transmission system that supplies DC series power via a transmission line to a plurality of relay devices provided with power separators on the input side and output side of the repeater a first current detection means for detecting a power supply current in a power supply system path between the power supply device and the repeater and temporarily turning off a first switch element; and a second current detection means that disconnects the current, the series circuit with the first and second switch elements is connected in a direction opposite to the connection point of the first and second current detection means. The relay device is connected between the relay device and the power supply system path on the input side of the repeater, and by forcibly restarting the power supply in the event of a power failure, the first relay device of the preceding relay device If a loop is formed in the power supply system downstream of this relay device while the switch element is temporarily disconnected, the power supply current is transferred to the second current detection means, and a failure in the relay transmission system is detected. A fault section search method characterized in that fault section determination is made possible by looping back a power supply circuit at the transmitting/receiving relay device immediately before a point.